Facial nerve outcome and extent of resection in cystic versus solid vestibular schwannomas in radiosurgery era.

OBJECTIVE Cystic vestibular schwannomas (CVSs) are a subgroup of vestibular schwannomas (VSs) that are reported to be associated with unpredictable clinical behavior and unfavorable postoperative outcomes. The authors aimed to review their experience with microsurgical treatment of CVSs in terms of extent of resection and postoperative facial nerve (FN) function and compare these outcomes with those of their solid counterparts. METHODS Two hundred-eleven VS patients were treated surgically between 2006 and 2017. Tumors were defined as cystic when preoperative neuroimaging demonstrated cyst formation that was confirmed by intraoperative findings. Solid VS (SVSs) with similar classes were used for comparison. Clinical data of the patients were reviewed retrospectively, including clinical notes and images, as well as operative, pathology, and neuroradiology reports. RESULTS Thirty-two patients (20 males and 12 females) with a mean age of 52.2 years (range 17-77 years) underwent microsurgical resection of 33 CVSs (mean size 3.6 cm, range 1.5-5 cm). Forty-nine patients (26 males and 23 females) with a mean age of 49.9 years (range 21-75 years) underwent microsurgical resection of 49 SVSs (mean size 3 cm, range 2-4.5 cm). All operations were performed via either a retrosigmoid or a translabyrinthine approach. Gross-total resection was achieved in 30 cases in the CVS group (90.9%) and 37 in the SVS group (75.5%). The main reason for subtotal and near-total resection was adherence of the tumor to the brainstem and/or FN in both groups. None of the patients with subtotal or near-total resection in the CVS group demonstrated symptomatic regrowth of the tumor during the mean follow-up period of 41.6 months (range 18-82 months). The FN was anatomically preserved in all patients in both groups. Good FN outcomes were achieved in 15 of CVS (grade I-II; 45.5%) and 35 of SVS (71.4%) surgeries at discharge. Good and fair FN functions were noted in 22 (grade I-II; 81.5%) and 5 (grade III only; 18.5%) of the CVS patients, respectively, at the 1-year follow-up; none of the patients showed poor FN function. CONCLUSIONS Surgery of CVSs does not necessarily result in poor outcomes in terms of the extent of resection and FN function. Special care should be exercised to preserve anatomical continuity of the FN during surgery, since long-term FN function outcomes are much more satisfactory than short-term results. High rates of gross-total resection and good FN outcomes in our study may also suggest that microsurgery stands as the treatment of choice in select cases of large CVSs and SVSs in the era of radiosurgery.